Modeling uptake kinetics of cadmium by field-grown lettuce

Department of Environmental Sciences, University of California, 900 University Avenue, Riverside, CA 92521, USA.
Environmental Pollution (Impact Factor: 4.14). 04/2008; 152(1):147-52. DOI: 10.1016/j.envpol.2007.05.004
Source: PubMed


Cadmium uptake by field grown Romaine lettuce treated with P-fertilizers of different Cd levels was investigated over an entire growing season. Results indicated that the rate of Cd uptake at a given time of the season can be satisfactorily described by the Michaelis-Menten kinetics, that is, plant uptake increases as the Cd concentration in soil solution increases, and it gradually approaches a saturation level. However, the rate constant of the Michaelis-Menten kinetics changes over the growing season. Under a given soil Cd level, the cadmium content in plant tissue decreases exponentially with time. To account for the dynamic nature of Cd uptake, a kinetic model integrating the time factor was developed to simulate Cd plant uptake over the growing season: C Plant=C Solution.PUF max.exp[-b.t], where C Plant and C Solution refer to the Cd content in plant tissue and soil solution, respectively, PUF max and b are kinetic constants.

Download full-text


Available from: Weiping Chen, Sep 16, 2014
  • Source
    • "Again, t U50 can be expressed in terms of GDD. By integrating the Michaelis-Menten and the uptake kinetics models, Chen et al. (2008, 2009b) characterized the Cd uptake by lettuce (Lactuca sativa L.) plants grown on an Entisol. The root density of growing plant is a function of its above ground biomass. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Background and aims The trace element uptake pro-cess of plants is a key factor in assessing the risks of trace element build-up in agricultural soils. Scarce information exists on the trace element dynamic up-take of plants grown in the field, especially on those potentially hazardous. In this study, the uptake process of As, Cd, Cu, and Zn in maize plants was quantified and characterized throughout the entire season. Methods Along two seasons, the uptake dynamics of field-grown maize plants in absorbing the soil borne trace elements was examined. Biomass production and the concentration of the elements in plant and soil solution samples were determined. A kinetic model was employed to characterize the uptake by plants. Results The kinetic parameters of the uptake process, maximum cumulative uptake rate, U max , time to reach 50 % of U max , t U50 , and reciprocal of the uptake rate, b U when followed throughout the season in terms of the plant's growing degree days remained constant between seasons and were element specific. In spite of the large amount biomass produced, maize plants extracted minute quantities of Cd and As. Increasing cumulative uptake rates of As, Cd, Cu, and Zn from the soil took place primarily in the early half of the growing season when the biomass accumulation was still less than 50 % of the maximum harvested bio-mass. The element-specific plant uptake factor (PUF), which denote the partition of trace elements between the soil solution and plant phases, decreased following Plant Soil
    Full-text · Article · Jan 2013 · Plant and Soil
  • Source
    • "In these studies, the partitioning of cadmium within the plant was analyzed. Also, modeling of cadmium uptake in lettuce was attempted (Chen et al., 2008). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Lettuce (Lactuca sativa) is a plant species that shows high accumulation of cadmium, a toxic heavy metal. Lettuce is therefore a good model both for identifying determinants controlling cadmium accumulation in plant tissues and for developing breeding strategies aimed at limiting cadmium accumulation in edible tissues. In this work, 14-day-old plants from three lettuce varieties were grown for 8 days on media supplemented with cadmium concentrations ranging from 0 to 50 microM. Growth, as well as Cd(2+), Zn(2+), K(+), Ca(2+), NO(3)(-), SO(4)(2-), Cl(-), phosphate, malate and citrate root an shoot contents were analyzed. The three lettuce varieties Paris Island Cos, Red Salad Bowl and Kordaat displayed differential abilities to accumulate cadmium in roots and shoots, Paris Island Cos displaying the lowest cadmium content and Kordaat the highest. From the global analysis of the three varieties, three main trends were identified. First, a common negative correlation linked cadmium tissue content and relative dry weight reduction in response to cadmium treatments in the three varieties. Second, increasing cadmium concentration in the culture medium resulted in a parallel increase in zinc tissue content in all lettuce varieties. A common strong positive correlation between cadmium and zinc contents was observed for all varieties. This suggested that systems enabling zinc and cadmium transport were induced by cadmium. Finally, the cadmium treatments had a contrasting effect on anion contents in tissues. Interestingly, citrate content in shoots was correlated with cadmium translocation from roots to shoots, suggesting that citrate might play a role in cadmium transport in the xylem vessels. Altogether, these results shed light on three main strategies developed by lettuce to cope with cadmium, which could help to develop breeding strategies aimed at limiting cadmium accumulation in lettuce.
    Full-text · Article · Oct 2010 · Journal of plant physiology
  • Source
    • "Cu . The new set of Cu uptake kinetic parameters that we determined in durum wheat therefore appeared more environmentally relevant than those available in the literature . Nevertheless , it should be kept in mind that the determination of such kinetic parameters is partly dependent on plant species / genotypes ( Lombi et al . 2001 ) , plant age ( Chen et al . 2008 ) and experimental conditions such as the composition of the nutrient solution . For the latter , Degryse et al . ( 2006 ) recently showed that plant uptake kinetics of a range of metals including Cu was driven in the low concentration range by diffusion limitations that occurred during the supply of free metals to roots , even when fre"
    [Show abstract] [Hide abstract]
    ABSTRACT: This study investigated (a) net Cu uptake kinetics in durum wheat (Triticum turgidum durum L.) exposed to free Cu2+ activities in solution ranging from 0.4 to 2,420nM and (b) the relative importance of plant uptake and soil’s ability to supply Cu2+ to the roots. Plant Cu flux showed a hyperbolic shape, enabling to estimate the Michaelis–Menten kinetic parameters (F max and K M) for durum wheat. Plant Cu flux was then compared with soil Cu flux as assessed by the Diffusive Gradient in Thin film technique on seven soil samples. This comparison suggested that the rate-limiting process of Cu bioavailability to durum wheat would be plant uptake kinetics in most contaminated soils with the exception of moderately contaminated, calcareous soils. However, theoretical considerations targeted soil’s ability to supply Cu as the rate-limiting process in most soils for Cu (hyper-) accumulator plants with requirement larger than that of common crop species. KeywordsBioavailability-Influx-Kinetics-Metal-Plant-Rhizosphere
    Full-text · Article · Jun 2010 · Plant and Soil
Show more